Decimation filters are used to convert a relatively high speed serial data stream, such as from a delta sigma modulator, and to a slower bit rate, wide word data. In the process of this decimation, certain advantageous filtering operations also occur.
One problem which is present in prior art decimation filters is that noise at frequencies above the base signal are aliased into the base signal, and once the noise is aliased into the base signal, it cannot be removed by conventional filtering techniques.
It can therefore be appreciated that a decimation filter which efficiently filters high frequency noise is highly desirable.